Age-related bone loss and osteoporosis are tremendous, and growing, public health problems. Approximately 10 million Americans over the age of 50 years already have osteoporosis by World Health Organization criteria, while 33 million more have "osteopenia" (analogous to "prediabetes");the total with low bone mass could reach 61 million by the year 2020. Given the scope of this problem, it is critical to obtain a better understanding of the factors determining the acquisition and loss of bone mass, from childhood to senescence. At a mechanistic level, there have been enormous advances in recent years in our understanding of the basic biology of aging;however, these concepts have not necessarily been tested for their relevance to skeletal aging. Thus, the goal of this U13 proposal is to bring together current concepts in aging research with ongoing and planned studies on the epidemiology, mechanisms, and prevention/treatment of age-related bone loss and fractures. The proposed conference will help to cross-fertilize the aging and bone research communities and seek to advance clinical and basic research on skeletal aging. Thus, the objectives of this workshop are 1) To briefly summarize key state-of-the-science basic and clinical findings on the consequences of aging and development and the role of genetic, environmental, and lifestyle/behavioral factors on alterations in skeletal integrity and fracture risk;2) To identify gaps in knowledge and needs for improved methodology/technology/resources to facilitate research on healthy skeletal aging;and 3) To identify opportunities for future research aimed at promoting skeletal health and reducing the risk of fractures across the lifespan. We will address these objectives within the context of our 6 Specific Aims, each associated with one of the sessions in the proposed conference agenda, which was developed in a partnership with NIH staff and members of the American Society for Bone and Mineral Research: To define the influence of nutrition and physical activity on bone accretion and loss (Aim 1);to identify the genetic and modifiable risk factors for bone loss and fracture (Aim 2);to define age-related changes in bone structure and cellular activity (Aim 3);to better understand basic mechanisms of cellular aging (Aim 4);to understand the physiological signals contributing to age-related bone loss (Aim 5);and, based on the proceedings of Aims 1-5, to identify a framework for future research in this field and the key questions that need to be addressed, both at a basic and clinical level (Aim 6). PUBLIC HEALTH RELEVANCE: Age-related bone loss and osteoporosis are tremendous, and growing, public health problems. Thus, the goal of this U13 proposal is to bring together current concepts in aging research with ongoing and planned studies on the epidemiology, mechanisms, and prevention/treatment of age-related bone loss and fractures. The proposed conference will help to cross-fertilize the aging and bone research communities and seek to advance clinical and basic research on skeletal aging.